Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description goes further and enumerates the actual return payload (price, date, week, previous value, trend direction, source, license, link), which is valuable given there is no output schema, though it omits how many records are returned or what an empty result looks like.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

A single sentence, front-loaded with the core purpose before listing return fields. It is dense but every clause earns its place; no filler or redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description correctly shoulders the burden of describing return values, and it does so thoroughly. It does not note that all four parameters are optional or how multiple matches are handled, which is a minor remaining gap.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 75%, so the schema already documents serie, ambito and producto. The description restates the serie-vs-producto dichotomy but adds nothing about ambito or limite, so it neither compensates for the gap nor extends the documented parameters.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource: 'Último precio publicado de una serie' or of products matching a text. It also enumerates the returned fields, so the agent knows exactly what it retrieves. It does not, however, name or distinguish itself from siblings like historico or buscar_producto, so it stops short of a 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is implied: pass an exact identifier, or a search text when the identifier is unknown. There is no explicit when-to-use/when-not guidance and no reference to alternatives such as buscar_producto for discovering identifiers or historico for longer time series, so it remains only implicit.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.